The effect of ad-interactor size on consumers’ purchase intention in social media in-feed ads

Purpose Previous studies on social media in-feed advertising have mainly explored the antecedent variables affecting ad effectiveness (e.g. interaction intention); however, they have not considered the impact of the interaction characteristic of ad-interactor size on ad effectiveness. This paper investigates the effect of ad-interactor size (large vs. small) on consumers’ purchase intention in in-feed advertising. Design/methodology/approach Five experimental studies using different social media (Weibo, Xiaohongshu, and WeChat Moments) and different types of products from real or virtual brands are conducted to examine the effects of ad-interactor size (large vs. small) on consumers’ purchase intention in in-feed advertising across different brand types (functional vs. symbolic). Findings The results of the study show that when the brand is symbolic, consumers under in-feed advertising with small ad-interactor size have higher purchase intention, in which the need for uniqueness plays a mediating role; when the brand is functional, consumers under in-feed advertising with large ad-interactor size have higher purchase intention, in which the need for belonging plays a mediating role. Originality/value This study breaks through the existing literature’s binary analytical perspective around social media in-feed ad interaction, and innovatively reveals that consumers are affected by the existing ad-interactor size when they are observers. We propose that interaction characteristics (such as ad-interactor size) are factors influencing ad effectiveness, enriching the literature in the field of social media in-feed advertising.